The present invention relates to connecting plates mounted in a battery holder for containing a number of columnar batteries for use in an electric vehicle or the like and to a method of producing the same.
The present application is based on Japanese Patent Application No. Hei. 9-279257, which is incorporated herein by reference
As a member for connecting plural batteries in series or in parallel, conventionally, a connecting plate 100 shown in FIGS. 25(A) and 25(B) is proposed.
The connecting plate 100 comprises a molded resin board 103 and bus bars 102 which are integrally molded with a resin. The bus bars 102 respectively connect to two batteries 101. In a molded resin board 103 of the connecting plate, a hexagonal window 103a and a rectangular window 103b through which electrode holes 102a at the ends of the batteries 101 are exposed are formed, The two batteries 101 are connected to each other by fastening the bus bars 102 respectively to nut-shaped positive and negative electrodes 101a and 101b by bolts 104. Also a ring terminal 105 partially constituting a voltage detection circuit is connected to one of the windows or the hexagonal window 103a. A fuse case 107 is connected in series to the other end side of an electric wire 106 which is connected at one end to the ring terminal 105. The other end of the electric wire is connected to an ECU which is not shown. A fuse 108 is housed in the fuse case 107. The ends of the fuse are connected to electrical contact portions 109a of female terminals 109 connected to the electric wire 106, respectively.
FIG. 26 shows another example of a connecting plate of the prior art.
In the connecting plate 100', plural L-shape bus bars 102, respectively having connecting legs 102b' of different lengths are moldingly fixed by a molded resin board 103. One end of each of the connecting legs 102b' protrudes from one side edge of the molded resin board 103. Ends on one side of electric wires 106 are welded to the protruding ends, respectively. The other ends of the wires are connected via a fuse case 107' to an ECU which is not shown.
In the fuse case 108', two L-shape pressure contact terminals 111 are opposingly disposed on a case substrate 110. The electric wires 106 are welded to basal plates 111a of the pressure contact terminals 111, respectively. Lead wires 108a' of fuses 108 are connected by pressure contact to slots 111c of pressure contact pieces 111b upstanding from the basal plates 111a, respectively.
The connecting plate 100 of FIG. 25 has many connecting portions in one circuit. In the voltage detection circuit, for example, there are six connecting portions indicated by letters a, b, . . . , and f. The number of parts is large. Therefore, there is a fear that the reliability of electrical connection is impaired. Furthermore, a work of fastening bblts must be conducted while holding respective ring terminals 105 one by one by a hand. As the number of electric wires to be connected is larger, therefore, the works of laying and routing the electric wires become more cumbersome and difficult.
By contrast, in the connecting plate 100' of FIG. 26, the L-shape bus bars 102' of different dimensions are used. Therefore, the plate has difficulties in cost and production management. In the same manner as the connecting plate 100, the number of parts is large and there are many connecting portions in one circuit (five portions a', b', . . . , e'). Moreover, the connecting plate has a problem in that the welding portions between the electric wires 106 and the connecting legs 102b' must be protected.
Furthermore, the electric wires 106 for the connecting plates 100 and 100' are directly connected to the batteries 101, and therefore an adequate protecting structure may be required. However, such protecting structure is complicated since bulky members such as the fuse cases 107 and 108' are attached to the electric wires 106.
FIG. 27 shows a structure in which batteries for an electric vehicle or the like are directly connected to one another without using connecting plates. In each of rectangular batteries 101', the positive and negative electrodes 101a' and 101b' are juxtaposed in one end side. Adjacent batteries are connected to each other by a main power source wire 112. An electric wire 106 (a voltage detection circuit) which has a fuse case 107 in the same manner as FIG. 25 is connected to a required electrode 101b'.
Also in this case, in the same manner as described above, the number of parts is large (the voltage detection circuit). Since the electric wires have many exposed portions, it is dangerous. Furthermore, the main power source wire 112 and the electric wire 106 of the voltage detection circuit intersect with each other, so that the wiring is complicated. This often causes the wiring to be erroneously conducted.
In the cases of the connecting plates 100, 100', it may be reasoned to form the connecting electric wire 106 in the molded resin plate 103 by insert molding.
However, a group of electric wires 113 are rigidly secured within a molded resin plate 114 but set free outside by the conventional insert molding as shown in FIG. 28 and this allows stress to be concentrated in the root portion 113a of the electric wires 113 as the boundary portion. In an extreme case, slight external force acting on the root portion 113a may result in rupture that portion. In order to prevent this situation, the group of electric wires 113 may be bound with a band 115 for fixing purposes or fixed by providing fixing means in part of or on the periphery of the molded resin plate 114. Even in this case, such work is done after the insert molding operation and it is impossible to eliminate the concentration of stress in the root portion 113a.
Moreover, one of the factors causing such a rupture to the root portion 113a of the electric wire 113 is biting in an electric-wire mounting grooves 117 in the exit portion between the top and bottom forces.
In the conventional insert molding of electric wire, molten resin forced into a mold 114 from the nozzle 119 of a molding machine 118 is higher in heat-resistant temperature than the insulating cover of the ordinary electric wire 113 as shown in FIG. 29, which results in raising cost because a heat-resistant electric wire such as what is covered with polyimide resin has to be used.